This invention relates to an assembly for use during endoscopic surgical procedures. More specifically, it relates to access an assembly which provides a sealed passageway for the insertion and withdrawal of surgical instruments during endoscopic surgery.
During an endoscopic surgical procedure, small openings through the body wall are made to provide access to the surgical site within the body cavity. In many procedures, particularly abdominal procedures, the body cavity is "insufflated" with pressurized carbon dioxide to inflate the cavity and separate body organs from one another. The separation of body organs creates a space within the body cavity at the surgical site to enable the surgeon to safely carry out surgical procedures.
During endoscopic surgery, an access device is often used to provide a passageway for receiving surgical instruments through a small opening into the body cavity. When the body cavity is insufflated, it becomes necessary for the device to not only provide a passageway, but also seal the opening to prevent the escape of the pressurized carbon dioxide gas from the body cavity. A conventional access device which has found widespread use is a trocar cannula. A cannula is typically a rigid assembly which has a housing and a tubular sleeve extending from the housing through the small opening in the body wall to provide the passageway into the body cavity. The cannula housing contains a valve such as a flapper valve which enables the passage of instruments through the cannula and seals the passageway when the instrument is removed. Unfortunately, the rigidity of the cannula can make it traumatic to the site on the surgical patient where the small opening is made to provide the passageway into the body cavity. Additionally, it is sometimes necessary to thread or "bolt" the cannula to the patient because the cannula may be inadvertently pulled from the opening when a surgical instrument is removed from the cannula. Further, since the sealing valve is in the cannula housing, the cannula may limit the depth of penetration of the surgical instrument through the cannula into the body cavity. Finally, the flapper valve and other seal designs which have been contemplated for use with the cannula make it undesirably difficult to remove tissue samples from the body cavity during the endoscopic surgical procedure.
Alternatives to the conventional cannula for providing access and simultaneously sealing the passageway when instruments are removed from the device have been described. For example, U.S. Pat. No. 5,366,478 describes an inflatable toroid which provides a seal when inflated. Endoscopic instruments, or alternatively, the surgeon's hand can penetrate through the lumen of the toroid. The lumen conforms to the shape of the instrument when the instrument is passed through it to maintain a seal. In addition, when the toroid is inflated, it becomes conveniently fixed within the opening in the patient's body wall, and prevents inadvertent removal when instruments are withdrawn from the device. Tissue samples can be removed readily from the inflated torid. A similar inflatable device is described in U.S. Pat. No. 5,389,080. These devices overcome some of the problems associated with the use of rigid cannulas.
Unfortunately, the inflatable access devices described in the literature are unduly bulky. Therefore, it may become difficult to initially place a surgical instrument adjacent the opening of the passageway of the inflated device because of the flexible nature of the inflated material. In other words, when the device is inflated, it does not provide a clear, well-defined passageway into the interior lumen of the access device. Consequently, it is possible that the inflated material may tear upon inadvertent contact between the surgical instrument and the material when the surgeon struggles to find the interior passageway of the access device. In addition, these inflatable devices may be difficult to manufacture in a cost effective manner. Furthermore, the material from which the inflatable device is made, particularly the internal lumen which provides the passageway, may create undue friction for the surgeon when a surgical instrument is inserted and withdrawn from the device. Finally, because of the bulky nature of these devices, the depth of penetration of instruments inserted through them may still be undesirably limited.
In view of the continuing need to improve access devices which can simultaneously provide a seal during endoscopic surgery, what is needed is an inflatable device which overcomes certain deficiencies inherent in inflatable devices previously described. Specifically, a device is desired which provides a clear passage when inflated to prevent inadvertent rupture of the inflation material. The device would also be easy to manufacture for cost effectiveness. It would provide a low profile so that the entire length of endoscopic instruments could be utilized within the body cavity. It would seal efficiently yet provide for minimal friction when instruments are inserted or withdrawn from the inflated device. It would also be less bulky and easier to handle.